To locate the link to your Affiliate Details Page where Affiliates can request to promote your product go to your Seller Dashboard. Next to the names of your products you will see three-dot icon (⋮), click that to open the menu and select Affiliate Details Page.
This is the link you will want to give to your potential affiliates to request to promote your product.
The link will be in the format seen in the sample link below. The numbers at the end of the link are your Product ID number.